In semiconductor device manufacturing, during the fabrication of integrated circuits (ICs), many process steps in the manufacturing sequence are performed in reduced pressure environments including high vacuum conditions. Generally, these processes, such as etching processes, deposition processes and cleaning processes, require extremely clean or contaminant-free conditions and precise control of the gaseous environment within which the device is processed. Moreover, these reduced pressures are suitable for processing devices using plasma. Often times, for example, plasma is utilized to assist etching reactions or material deposition on a substrate.
In order to achieve high vacuum conditions (of order milliTorr and less), turbo-molecular pumps (TMP) are customarily utilized. Akin to axial flow turbo-machines, TMPs include a plurality of pumping stages, wherein each stage has a rotor blade row (i.e., rotating blades) that is coupled to a common rotatable hub, followed by a stator blade row (i.e., stationary blades) that is coupled to the pump casing. Generally speaking, the operation of a TMP mimics that of a turbo-machine in its mechanics with the exception that the design of a TMP is governed by free molecular flow dynamics rather than continuum fluid dynamics. Moreover, in order to deliver suitable pumping speeds to a vacuum processing system, the rotational speed of the TMP rotor is generally in excess of 20,000 to 100,000 RPM (revolutions per minute). In doing so, these pumps can achieve process pressures significantly less than several hundred mTorr (or thousandths of an atmosphere, ATM).
Due to the high rate of rotation of the TMP rotor and the corresponding angular momentum and energy stored in that rotation, there exists a risk that a catastrophic failure of the TMP could lead to a compromise in the coupling of the TMP to the vacuum processing system or possibly a complete detachment of the TMP. If a TMP becomes loose or breaks free of the vacuum process system, the results could be catastrophic. Such a catastrophic failure could include the TMP being carried from the vacuum process system by its angular momentum and dangerous process gasses leaking from the vacuum process system. If a catastrophic failure were to occur, the TMP could damage other parts of the vacuum process system or even injure a vacuum process system operator.
Conventional devices for containing a catastrophic failure of a TMP typically consist of a large base frame that is bolted to the vacuum process system. These conventional devices generally present a large footprint on a tool that includes the vacuum process system, which not only increases costs, but also makes installation or removal of such devices quite complicated. For instance, an operator may have to loosen as many as twenty enormous bolts to gain access to a TMP. Access to the bolts is hampered by the large footprint of the conventional device, which results in a lack of workspace to remove the typically large bolts. Additionally, because the conventional TMP containing devices constrain every degree of freedom a TMP may have, alignment and installation of a TMP to a vacuum process system becomes even more difficult, time consuming, and therefore costly.